zinc paint under insulation

[heaterguy]

I apologize if this topic has been discussed, but the search function is down and Google didn't pull up anything on this topic.

A paint spec says for carbon steel, "When using inorganic Zinc under insulation, do not apply on piping or vessels operating between 50F and 250F as the zinc reverses polarity and contributes to the corrosion of carbon steel."

May someone offer a link to a paper or article that further describes the problem with zinc coatings under insulation?

TYIA,

HG

 

[0707]

Go to, maybe it halps

http://www.international-pc.com/pc/technical/tech_papers/Corrosion_under_insulation_mjm02_2001.PDF

luis marques

 

[rconner]

Polarity reversals involving zinc and temperature in general (once the site search comes back up, I think you will find this has been mentioned in some threads in various forums e.g.

http://www.eng-tips.com/viewthread.cfm?qid=177457&page=4

) may be a rather complex subject, with perhaps some "it depends" qualifications. It appears this general subject has been studied e.g. at

http://books.google.com/books?id=C-...&sig=VP-Qe3TAe7aZ4KX305IdCfimEuo#PRA1-PA1,M1.

 

[SJones]

http://www.nace.org/nacestore/assets/freestandardsreports/RP019804.pdf

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/